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Histone IIb1 from immature testes of rainbow trout has been highly purified and then succinylated or maleylated and treated with trypsin. Thirteen tryptic peptides have been purified, with a total composition accounting for all amino acid residues in intact trout IIb1. Eleven of these peptides have been sequenced completely, and partial sequences have been obtained for the other two peptides.

Acetylation of histones has been observed in both the spermatocytes and spermatids from developing trout testis. In the former cell type, both histone synthesis and extensive acetylation occur, whereas in the spermatids there is histone acetylation, but very little synthesis. The half-life of the histone acetyl groups is approximately 23 hours in the pre-spermatid cells. It is suggested that the acetylation of histones in spermatids may serve a different function from the corresponding modification observed in the earlier testis cells.

Trout testis cells were labeled with [3H]arginine or lysine and inorganic [32P]phosphate. Cells at different stages of spermatogenesis were separated by their differing velocities of sedimentation in serum albumin gradients at one gravity. The basic proteins from each of these cell types were separated and analyzed for radioactivity in starch gels. Most of the histones were synthesized and phosphorylated in diploid cells of sedimentation velocity 2.8 and 3.5; very little synthesis or phosphorylation of histone occurred in the spermatids. Although different rates of histone synthesis and phosphorylation were found in different cell types, the ratios of synthesis to phosphorylation were close to unity in each case. The positive correlation between these and the rates of DNA synthesis suggest that the phosphorylation of histone may be required for the correct binding of histone to DNA. The half-life of phosphate in histones varied from 8 to 13 hours in cells actively synthesizing histones but was very long in protamine stage spermatids. In addition, labeled arginine did not appear in unmodified histone IV until 21 hours after the start of the incorporation suggesting that newly synthesized histone IV may pass through a series of modifications before reaching its final unmodified state.

Various factors which have an important economic bearing upon the production of sintered porous media are reviewed. In particular, reference is made to the manufacture of porous media from: (a) spherical powder, (b) irregular powder, (c) wire, (d) fibres, and also combinations of these materials. Processes considered include: (1) gravity sintering, (2) pressure sintering, (3) press compaction and sintering, (4) roll compaction and sintering. Consideration is also given to the fabrication of porous media.The significance of various economic factors is discussed in relation to end-product properties and applications.

The development of encephalography has provided a new method of precision for the examination of organic diseases of the brain. During the past three years we have used this procedure in five hundred and three cases and have found it of great value in the interpretation of symptoms and prognosis. This procedure, while not devoid of dangers, if carefully used gives information concerning the nature and extent of cerebral pathologic conditions which offsets the hazards involved.The interpretation of the roentgen shadows in the encephalogram is dependent on the physical relations existing in the skull. Collections of air replacing fluid-filled areas result in the facilitation of the passage of the x-rays. In the normal encephalogram one finds a constant general pattern of cerebral topography. This is subject to alteration by various pathologic processes especially common in dementia paralytica, as shown by inflammatory arachnoiditis and atrophic changes.In the normal brain

The sequences of the first 25 residues of histone III, and the first 22 residues of histone IIb2, from trout testis have been determined on an automatic protein sequencer. The amino-terminal sequence of trout-testis histone III is identical to the corresponding region of calfthymus histone III, whereas the trout-testis histone IIb2sequence differs from that of calf-thymus histone IIb2at several positions in the amino-terminal region. Several in vivosites of acetylation of these trout-testis histones have also been determined, by the same automated procedure. In addition to the two main sites at lysyl residues 14 and 23 acetylated in calf-thymus histone III, a lower degree of acetylation at two other sites, lysyl residues 9 and 18, has been detected. Four sites of acetylation have also been detected in trout-testis histone IIb2, at lysyl residues 5, 10, 13, and 18. When the amino-acid sequences around the acetylated lysyl residues of different histones are compared, striking similarities are seen. The methods used in these studies should prove useful in elucidation of the locations of chemically stable modifications in other proteins.

Trout testis cells were incubated with [3H]arginine and lysine and inorganic [32P]phosphate. Histones were extracted with acid and the major fractions (I, IIb1, IIb2, III monomer, and IV) were resolved by chromatography on Bio-Gel P-10. The profile of 32P incorporation was time dependent. When the phosphorylated histones in each of the major fractions were resolved from unphosphorylated species by starch gel electrophoresis, about 40 to 50% of histone I, 15 to 20% of histone IIb1, 5% of histones IIb2and III, and 30 to 40% of histone IV was found to be phosphorylated. These different levels for each histone suggest that in each case phosphorylation may have a separate function other than, or in addition to, the usually postulated one of direct gene derepression.

The basic principles of the forging of powder preforms are explained and the advantages of the process indicated. The development of the Petro-Forge system and the necessary equipment are described, together with an exhaustive series of tests devised to determine the effect of production variables on the product. The wide range of products obtainable is illustrated by examples.

During spermatogenesis in trout testis, histone IV is extensively modified by acetylation and phosphorylation. To examine the relationship of synthesis of histone IV to its modification, histone IV labeled with [3H]aminoacids and inorganic [32P]phosphate was prepared from testis cells by acid extraction and column chromatography. Purified histone IV was resolved by starch gel electrophoresis into 10 bands, of which nine are modified by acetylation and/or phosphorylation. In the first 4 hr of labeling, the diacetyl-histone IV band showed the highest proportion of [3H]aminoacid label. After 12 hr of incorporation, more label was found in the triacetyl and tetraacetyl bands. A significant amount of amino-acid label in the two major bands (the unsubstituted and monoacetyl bands) of histone IV was not seen until 16 hr of incubation. From 1 to 12 days, the proportion of label in the unsubstituted and monoacetylated bands increased, while that in the tetra-, tri-, and monoacetyl bands decreased. Very little [3H]aminoacid was found in the phosphorylated bands of histone IV in the first 12 hr. However, after 16 hr about 20% of the total 3H was found in the phosphorylated bands. The proportion increased to 33% and remained at this level between 1 and 8 days, but, by 16 days, had decreased to 12% of the total.These data suggest that an “obligatory” acetylation of recently synthesized histone IV is involved in the correct binding of newly synthesized histone IV to DNA. We propose that ε-amino acetylation of lysyl residues 5, 8, 12, and 16 neutralizes their positive charges and allows the NH2-terminal region of histone IV to assume the correct conformation (in this case, an α-helix), and fit into the major groove of DNA. Deacetylation then “locks” histone IV to DNA by ionic linkages. The biological significance of phosphorylation of histone IV is not known.

After completion of the synthesis of protamine in the cytoplasm of rainbow trout testis spermatid cells, the seryl residues of the molecule are phosphorylated (Ingles, C. J., andDixon, G. H. (1967) Proc. Nat. Acad. Sci. U. S. A., 58, 1011). Amino acid sequence studies (Ando, T., andWatanabe, S. (1969) Int. J. Protein Res., 1, 22) of three components of rainbow trout protamine each containing 4 seryl residues show that 3 seryl residues occur together in the NH2-terminal half of each protamine in the sequence Arg-Ser-Ser-Ser-Arg and the 4th in the COOH-terminal half of the molecule in the sequence Val-Ser-Arg. It is shown here that tryptic phosphopeptides in which each seryl residue is recovered in the phosphorylated form can be isolated from protamine labeled with [32P]phosphate in vivo. In addition, a further series of phosphoseryl peptides corresponding to the sequence Arg-Ser(PO4)-Ser(PO4)-Arg have been isolated, and it is suggested that these are derived from an as yet unsequenced component of rainbow trout protamine. An ionophoretic method for determining whether a given seryl residue is phosphorylated is also described.

A colorimetric ninhydrin method has been applied to the quantitative estimation of amino acids and peptides on paper chromatograms. This method is suitable for the analysis of enzymic transpeptidation reactions. A procedure for the purification of filter paper for chromatography has been developed.

Proteases from the sea anemone have the same zymogen activation and active site chemistry as the proteases of the mammalian pancreas. One of them has kinetic properties remarkably similar to chymotrypsin. The findings suggest a common ancestry for the digestive process of mammals and coelenterates.

The complete amino-acid sequences of the alpha chains of the common genetic variants of human haptoglobin confirm that the α2chain has arisen by partial gene duplication of the Hp1locus. A homology in sequence between a portion of the haptoglobin alpha chain sequence and a series of Bence Jones light chains suggests that the functional similarity between haptoglobin and immunoglobin G may reflect a common evolutionary origin.

Preoperative and postoperative plasma renin activity (PRA) was determined serially in 23 patients undergoing operation for renovascular hypertension. In 18 patients PRA became normal within five days postoperatively and preceded normalization of the blood pressure. Two patients, with elevated PRA postoperatively, required secondary nephrectomy, following which PRA and blood pressure became normal. These 20 patients have been observed for an average of 29 months; 15 have had an excellent result (diastolic blood pressure of 90 mm Hg or less) and five a good result (blood pressure as above, but requiring drugs). In contrast, the three patients with persistent elevation of postoperative PRA had refractory hypertension and one hypertensive death occurred. Measurement of PRA following operation for renovascular hypertension provides a more direct and immediate assessment of operative success or failure than determination of blood pressure alone and allows a prediction of long-term results.

The properties of alloy steels produced by powder-metallurgy techniques, as compared with those of conventional cast or wrought alloy steels, are reviewed. Factors affecting the production of alloy steels by powder-metallurgy techniques are enumerated, and the importance of adequate mechanical properties coupled with ease of processing is emphasized. The paper covers the preparation and testing of a wide range of low-alloy steels including copper steels, nickel steels, and complex steels; these being made up either from elemental powders or from pre-alloyed or complex powders. The influence of various alloying elements upon the mechanical properties of the steels produced is indicated, and the merits of the various compositions investigated, are discussed.The response of powder-metallurgy alloy steels to quenching is next determined, and the effects of the elements carbon, manganese, nickel, copper, and molybdenum upon the hardcnability of alloy steels is summarized in the form of depth-hardening curves. The use of precipitation-hardening as a means of improving the properties of low-alloy steels is also investigated for a wide range of copper-containing steels. It is demonstrated that by employing this technique it is possible to obtain very significant improvements in properties, together with some processing advantages.

Experiments have shown that in the cat, the rostral portion of the mesencephalic tegmentum and its continuation into the hypothalamus are involved in the act of walking. In the absence of the cerebral cortex and thalamus, a number of reflex patterns are present which would necessitate descending pathways other than the corticospinal tracts, i. e., tracts of an extrapyramidal nature. There are a number of such pathways, any one of which may be essential for such descending conduction.1There have been several observations which show that stimulation of the mesencephalic tegmentum in the region of the red nucleus in the monkey and the cat produces ipsolateral flexion and contralateral extension in the fore limbs and varying responses in the hind limbs. This may represent one of the components of walking and other reflex activities of the mesencephalic tegmentum, and it was with the purpose of a further analysis of

At a late stage of spermatogenesis in rainbow-trout testis, the entire complement of histones is replaced by newly synthesized protamine and histones are extensively phosphorylated and acetylated. Tryptic digestion of purified histones labeled by incubation of testicular cells with [32P]phosphate shows that phosphorylation occurs at a small number of seryl residues.Histone I (lysine-rich) is phosphorylated in the sequence Lys-Ser(PO4)-Pro-Lys, which is located in the lysine-rich C-terminal region of the molecule. Histones IIb1(slightly lysine-rich) and IV (glycine, arginine-rich) give rise to the same phosphopeptide, Ac-Ser(PO4)-Gly-Arg, which comprises the amino terminus of each histone. Thermolysin digests of phosphohistones IIb1and IV also released a phosphopeptide with composition corresponding to the first six residues of histone IV: Ac-Ser(PO4)-Gly-Arg-Gly-Lys-Gly. An α-helical model of the N-terminal region of histone IV shows that this region is a possible DNA-binding site. Phosphorylation at serine 1 together with ε-amino acetylation at lysines 5, 8, 12, and 16 (observed in histone IV from trout testis) could profoundly modify ionic interactions and lead to an „unzipping” of histone IV from DNA

Extensive acetylation of four of the five major histones occurs during spermatogenesis in rainbow trout testis. At least one site of acetylation can be detected in histone IIb1, two sites in IIb2, two sites in histone III, and four sites in histone IV. No acetylation of histone I has been observed. The major site of acetylation in IIb1is at lysyl residue 5. This region of the IIb1molecule is homologous to the corresponding region in histone IV.

A cell-free protein-synthesizing system from rainbow trout liver can initiate de novosynthesis in the presence of exogenous messenger RNA if the system is previously incubated for 60 min. Polyuridylic acid and polyguanylic uridylic acid can be used as synthetic messenger RNA to test for the ability of the system to reinitiate synthesis. Low molecular weight RNA isolated from protamine stage testis microsomes actively stimulates the incorporation of [14C]arginine and [35S]methionine into acid-insoluble material. Starch gel and polyacrylamide gel fractionation show that both isotopes are incorporated in vitrointo protamine and histone. The protamine product was characterized by separately incorporating [14C]arginine, [14C]proline, and [14C]serine into in vitrosynthesized material and carrying out ten sequential Edman degradations. The order of appearance of labeled amino acids during this process was consistent with the known sequence of rainbow trout protamine.

Spermatogenesis in rainbow trout provides a favourable system for the study of the striking changes in the population of basic nuclear proteins in the chromatin of the developing sperm. Methods are described for the isolation and characterization of the basic proteins of testis both on the preparative and the micro-scale. Large volume changes occur as cells pass through the series of developmental changes and they may be readily separated by velocity sedimentation at one gravity. This enables a study to be made of the timing of particular biochemical events during development. The process whereby the histones are removed and replaced by newly synthesized protamines is examined in detail and possible mechanisms discussed. The role of post-synthetic modification of basic proteins by phosphorylation and acetylation is examined and the sites of these modifications in the primary sequence of protamine and histones determined. From a study of the timing of the modification reactions, it appears that phosphorylation and acetylation play an important role in modulating the correct binding of highly basic regions of histones to DNA while acetylation may also be involved in de-stabilizing the tight complexes between DNA and the basic NH2-terminal regions of histones IIb1, IIb2, III and IV as a preliminary to their replacement by protamine and the formation of the very compact nucleo-protamine of the mature sperm.

We analyzed continuous GPS data collected from 2002–2020 to characterize slow slip events (SSEs) in and near the Nicoya Peninsula, Costa Rica. These data are bisected by the 5 September 2012 Mw7.6 earthquake. The displacement time series contain multiple signals, including plate convergence, plate interface locking, coseismic and postseismic deformation, seasonal oscillations, SSEs, and noise. GPS‐measured coseismic and postseismic displacements associated with the Mw7.6 earthquake are modeled and removed by a step function plus multiple timescale relaxation processes with four characteristic times: 11, 94, 470, and 1,865 days. Seasonal oscillations are eliminated using a multichannel singular spectrum analysis (M‐SSA). Ten major SSEs (Mw> 6.6) are observed in the remaining time series, with a constant recurrence interval of 21.7 ± 2.6 months. SSEs occur in both shallow (~10 km) and deep (~35 km) portions of the plate interface, but the latter last longer and have larger magnitudes. There is minimum to no slow slip in the Mw7.6 seismic rupture area and a persistent slow slip patch beneath the Nicoya Gulf entrance. Despite strong earthquake‐related stress perturbations, the inter‐SSE locking status on the megathrust is very similar between the late and early stages of the earthquake cycle and includes locked patches that ruptured in the 2012 earthquake or continue to rupture via SSEs. Some locked patches offshore south of the Nicoya Peninsula did not rupture in 2012, do not participate in SSEs, and may be indicative of supercycle behavior, that is, strain accumulation over several seismic cycles. These areas warrant heightened monitoring. Slow slip events (SSEs) release strain energy in Earth's crust that accumulates due to plate motion and frictional locking on the boundaries between plates. SSEs are similar to earthquakes but are less damaging, since strain is released slowly, over weeks or months. We used GPS measurements with millimeter precision to study SSEs in Northwestern Costa Rica between 2002 and 2020 and compared them to the pattern of strain accumulation over the same period. We find that these events happened about every 22 months, and the repeat time is unchanged by the 5 September 2012 Mw7.6 Costa Rica earthquake. Locking patterns also remain similar before and after this earthquake. However, some locked zones did not rupture in the 2012 earthquake or earthquakes in the last few decades and do not participate in SSEs. These areas may represent zones of higher seismic risk in the future. Slow slip events >Mw6.6 in northwestern Costa Rica occurred every 21.7 ± 2.6 months based on data from 33 GPS stations between 2002 to 2020Slow slip recurrence/distribution and inter‐transient strain accumulation patterns were unchanged by the 5 September 2012 Mw7.6 earthquakeSome inter‐transient locked patches offshore did not rupture in 2012 and do not participate in slow slip events

Estimates of flood susceptibility and land loss in the world's coastal regions depend on our knowledge of sea level rise (SLR) from increases in ocean mass and volume, as well as knowledge of vertical land motion. Conventional approaches to the latter include tide‐gauge and Global Positioning System (GPS) measurements relative to well‐anchored monuments few meters below the surface. However, in regions of rapid Holocene sedimentation, compaction of this material can add a significant component to the surface lowering. Unfortunately, this process has been difficult to quantify, especially for the shallowest material above the monument. Here we use a new technique, GPS interferometric reflectometry, to estimate the rate of this process in the Mississippi Delta and the eastern margin of the North Sea. We show that the rate of shallow compaction is comparable to or larger than the rate of global SLR, adding 35% and 65%, respectively, to the rate of relative SLR by 2100. Sea level change is influenced by vertical motion of the sea surface as well as vertical motion of the land in coastal areas. Tide gauges and GPS are two conventional approaches to measure coastal vertical land motion (VLM). GPS conventional positioning determines the vertical component of position changes resulting from displacements beneath the monument foundation. However, quantifying shallow VLM that occur above the base of monument has not been possible so far. In regions of rapid Holocene age (roughly 11,500 yr before present) sedimentation such as river deltas and coastal alluvial plains, compaction of this material, if not countered by ongoing sedimentation, can add a significant component to the rate of coastal subsidence. Here, we use a new technique, GPS interferometric reflectometry, to estimate the rate of shallow VLM in two coastal regions with thick Holocene deposits, the Mississippi Delta and the eastern margin of the North Sea. We show that the rate of VLM from shallow compaction is comparable to or larger than the rate of sea level rise. Since many of the world's great coastal cities are built on river deltas with comparable Holocene sections, our results suggest that estimates of flood risk and land loss have been underestimated. Shallow displacement within the layer between the surface and the base of a GPS monument are measured using the GPS‐IR techniqueRates of shallow sediment compaction (SSC) are quantified at GPS sites in two coastal regions with thick and compressible Holocene depositsSSC amplifies rates of SLR in the Mississippi Delta and the east coast of the North Sea adding 35% and 65%, respectively, to SLR rates by 2100

Plant NLR proteins enable the immune system to recognize and respond to pathogen attack. An early consequence of immune activation is transcriptional reprogramming. Some NLRs have been shown to act in the nucleus and interact with transcription factors. The Rx1 NLR protein of potato binds and distorts double-stranded DNA. However, the components of the chromatin-localized Rx1 complex are largely unknown. Here, we report a physical and functional interaction between Rx1 and NbDBCP, a bromodomain-containing chromatin-interacting protein. NbDBCP accumulates in the nucleoplasm and nucleolus, interacts with chromatin, and redistributes Rx1 to the nucleolus in a subpopulation of imaged cells. Rx1 overexpression reduces the interaction between NbDBCP and chromatin. NbDBCP is a negative regulator of Rx1-mediated immune responses to potato virus X (PVX), and this activity requires an intact bromodomain. Previously, Rx1 has been shown to regulate the DNA-binding activity of a Golden2-like transcription factor, NbGlk1. Rx1 and NbDBCP act synergistically to reduce NbGlk1 DNA binding, suggesting a mode of action for NbDBCP’s inhibitory effect on immunity. This study provides new mechanistic insight into the mechanism by which a chromatin-localized NLR complex co-ordinates immune signaling after pathogen perception.

Texas is experiencing increasing seismicity, likely related to the oil and gas production process. We used satellite InSAR (Interferometric Synthetic Aperture Radar) to monitor surface deformation at three study sites in western Texas with similar geologic characteristics. The deformation data were compared to earthquake distribution, groundwater changes, volumes of produced and injected fluid, and calculated pore pressure change and Coulomb failure stress change to assess causes of deformation and seismicity. Site 1 experienced surface uplift due to fluid injection but no increase in seismicity. The average media properties were estimated based on the deformation using a poroelastic model. Site 2 experienced subtle surface subsidence and elevated seismicity. Subsidence here might reflect groundwater withdrawal. Simulated pore pressure changes using MODFLOW suggest the earthquakes are likely induced by fluid injection. Site 3 experienced significant surface subsidence and seismicity. InSAR time series, water level data, and oil/gas extraction history suggest that subsidence in the northern part of this site reflects oil/gas extraction, while subsidence in the southern part is mainly due to groundwater withdrawal. An Okada tensile model was used to derive the equivalent source strength causing the subsidence, then Coulomb failure stress changes associated with this source were calculated. We found that pore pressure change (simulated using MODFLOW) due to fluid injection is likely the main contributor to elevated seismicity at this site. Variations in oil/gas production activity, seismicity, and surface deformation between our three sites suggest the importance of local rock structure and media properties in determining susceptibility to induced seismicity. In recent years, both oil/gas production and earthquake number have increased in western Texas. This coincidence suggests at least some of the earthquakes are likely related to the oil/gas production process. We used sequential satellite images to measure surface deformation at three study sites in the Delaware Basin, western Texas. These three sites show different patterns of surface deformation and earthquake occurrence: (1) Site 1 has obvious uplift but no earthquakes; (2) Site 2 has little subsidence but many earthquakes; (3) Site 3 has significant subsidence and earthquakes. By analyzing temporal and spatial correlations between multiple independent data sets and the results of numerical models, we found the likely causes of the deformation and elevated earthquakes: (1) Surface uplift at Site 1 is due to fluid injection; (2) surface subsidence and earthquakes at Site 2 are probably related to groundwater withdrawal and fluid injection, respectively; and (3) the obvious surface subsidence at Site 3 reflects groundwater withdrawal in the south and oil/gas extraction in the north, while earthquakes are likely related to fluid injection. Since our model results rely on subsurface media properties, better assessment of whether an earthquake was or was not induced will require better knowledge of local rock properties. Increasing numbers of earthquakes in recent years south and southeast of Pecos city, Texas, are likely related to oil and gas productionInSAR time series deformation was used to distinguish the causes of deformation and to estimate media properties and reservoir dynamicsNumerical modeling suggests that pore pressure change due to fluid injection is likely the main contributor to the abnormal earthquakes

The verification of gain on extreme ultraviolet ion lines in elongated plasmas using optically thin intercombination lines from similar ions is proposed. New impurity-line identifications in laser-produced plasmas suggest that recent reports of gain at 58.23 Å may be inconclusive.

An elongated plasma of length ≈8 mm with an aspect ratio of ~6:1 has been formed by channeling a laser-produced plasma created in a point focus on a carbon surface. Densities of C^6+ ions near 10^16 cm^−3 were observed in a contracted region beyond the guiding channel, suggesting a use for short-wavelength amplification.

A NON-HISTONE chromosomal protein extracted from trout testis chromatin by 0.35 M salt, protein S, (ref. 1) has now been purified to homogeneity and its primary structure determined (Fig. 3) and shown to be identical with that of the thymus protein, ubiquitin2–4(originally called thymopoietin) and sequenced by Schlesinger et al.5. Ubiquitin was previously reported in chromatin by Goldknopf et al.6as a component of protein A-24 in which it is covalently bound by the α-carboxyl group of its C-terminal glycine to the ε-amino group of lysine 119 of histone H2A in an isopeptide linkage7. Goldknopf and Busch8have reported that protein A-24 is a component of the core nucleosomes of rat liver chromatin being present in quantities sufficient for it to be linked to H2A in 10–20% of the total nucleosomes. The present studies indicate clearly that ubiquitin can also occur as a free polypeptide in trout testis chromatin and is readily extracted by 0.35 M NaCl. Moreover, free trout testis ubiquitin (protein S) is rapidly released together with HMG-T (ref. 9) (and small amounts of Hl) during limited micrococcal nuclease digestion of trout testis chromatin and is probably also located in the linker regions of the chromatin. DNase I digestion does not release free ubiquitin preferentially10. In view of the pronounced biological effects of free ubiquitin on membrane adenyl cyclase of immature thymocytes3,4and the ability of ubiquitin to promote the differentiation of these cells into mature T cells3,4, its occurrence in chromatin raises the possibility of a role of ubiquitin in cell differentiation and differential gene expression.

PARTIAL gene duplication has been suggested as an important mechanism in the evolution of proteins1on the basis of a study of the repeating structure of the light (α −) chain of the human haptoglobin molecule controlled by the Hp2gene. Support for this hypothesis has come from the discovery in several unrelated proteins of homologous sequences of amino-acids. In ferredoxin from Clostridium pasteurianun, portions of the N-terminal and C-terminal halves are homologous2and these halves of the molecule may have arisen by partial gene duplication from an intermediate nonadecapeptide which in turn could have been derived by the same processes of duplication from an archetypal tetrapeptide2,3. Other examples of internal homology have been postulated in cytochrome C (ref. 3), the haemoglobin chains4and the light and heavy chains of immunoglobins5.

JOHN JOLY came of a remarkable lineage. His father's grandfather was a member of a French noble family. His mother, a German countess, whose family had been ennobled by Frederick the Great, was descended from Greek, Italian, and English ancestors. This mixture of blood, perhaps, may explain his ready sympathy with the most diverse personalities, his princely generosity which often gave to others what he denied to himself, and his versatility which enabled him to prosecute research in so many fields of knowledge, and to obtain æsthetic pleasure in the realms of art, literature, iusic and science.

By myostatic contracture we mean to designate a condition of permanent shortening in resting muscle, which is maintained in the entire absence of nerve impulses, the muscle having acquired, usually as the result of prolonged immobility, a new and shorter than normal resting length. Familiar examples are the contractures which limit the movement of joints after prolonged immobilization in plaster casts, the permanent shortening of muscles after division of their tendons, the paretic contractures due to the unequal paralysis of antagonistic muscle groups in anterior poliomyelitis and multiple neuritis and the rigidity seen in the latter stages of local tetanus.Muscles in myostatic contracture have approximately normal elasticity, but their ductility, i. e., their tendency to undergo permanent elongation when stretched, is greatly reduced.The muscle tested was the gastrocnemius of the white rat with sciatic nerve cut but circulation intact. The muscle was stretched with loads increasing by 10 gm. intervals with 2 minute cycles of stretching and rest. A weight of 10 gm. was applied for 1 minute and removed for 1 minute, then 20 gm. was applied for 1 minute and removed for 1 minute and so on up to 100 gm.In the first set of experiments the muscles were exposed to the air at room temperature while being stretched. Under these conditions a series of 10 normal muscles gave an average permanent elongation of 3.08 mm.; 10 muscles in contracture 15 days after section of the tendo achillis gave an average permanent elongation of 1.33 mm.; and 9 muscles in tetanus contracture gave an average permanent elongation of 1.28 mm. This marked decrease in ductility is not due to fibrosis. Histological sections of these muscles show no increase in connective tissue and only slight changes in the muscle fibers, such as a blurring of the cross striations.

There is an increased necessity of interest in the recognition of acute myocardial infarction (AMI) occurring during operation or in the early postoperative period. Measurement of serum creatine phosphokinase (SCPK) activity has proven to be useful in the diagnosis and verification of AMI in nonsurgical patients. Fifty-eight patients undergoing thoracic, cardiac, and abdominal operations were studied with preoperative and serial postoperative determinations of SCPK. A marked rise in SCPK activity, related to tissue trauma and injury, occurred postoperatively with the maximal level recorded at 24 to 48 hours after operation, followed by a decline toward normal in five days. Three patients suffered acute myocardial infarctions and had an increased magnitude and duration of SCPK elevation. The results of this study define the pattern of postoperative SCPK activity that normally can be expected, and provide information that may be useful in the recognition of postoperative AMI.

At a time where high levels of stress are reported in the veterinary profession, this study explores the challenges that veterinary graduates encounter when they enter general (first opinion) practice. Participants had written reflective accounts of their ‘Most Puzzling Cases’ for the postgraduate Professional Key Skills module of the Certificate in Advanced Veterinary Practice, offered by the Royal Veterinary College. Reasons that a case was puzzling, or became challenging, were thematically analysed. Fifteen summaries were analysed. Three core themes were identified: ‘clinical reasoning’, centred on the limitations of pattern recognition and the methods used to overcome this; the ‘veterinary healthcare system’, focusing on the need for continuity of care, time pressure and support in the transition to practice; and the ‘owner’, looking at the broader clinical skills needed to succeed in general practice. Clinical reasoning was raised as an issue; discussion of when pattern recognition is not appropriate and what to do in these cases was common. A lack of experience in general practice case types, and how to best operate in the resource‐constrained environment in which they present, is the likely cause of this, suggesting that a greater focus on the primary care paradigm is needed within veterinary education.